How to write to a file in java using FileOutputStream

Earlier we saw how to create a file in Java. In this tutorial we will see how to write to a file in java using FileOutputStream. We would be using write() method of FileOutputStream to write the content to the specified file. Here is the signature of write() method.

public void write(byte[] b) throws IOException

It writes b.length bytes from the specified byte array to this file output stream. As you can see this method needs array of bytes in order to write them into a file. Hence we would need to convert our content into array of bytes before writing it into the file.

Complete Code: Writing to a File

In the below example we are writing a String to a file. To convert the String into an array of bytes, we are using getBytes() method of String class.

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class WriteFileDemo {
   public static void main(String[] args) {
      FileOutputStream fos = null;
      File file;
      String mycontent = "This is my Data which needs" +
	     " to be written into the file";
      try {
          //Specify the file path here
	  file = new File("C:/myfile.txt");
	  fos = new FileOutputStream(file);

          /* This logic will check whether the file
	   * exists or not. If the file is not found
	   * at the specified location it would create
	   * a new file*/
	  if (!file.exists()) {
	     file.createNewFile();
	  }

	  /*String content cannot be directly written into
	   * a file. It needs to be converted into bytes
	   */
	  byte[] bytesArray = mycontent.getBytes();

	  fos.write(bytesArray);
	  fos.flush();
	  System.out.println("File Written Successfully");
       } 
       catch (IOException ioe) {
	  ioe.printStackTrace();
       } 
       finally {
	  try {
	     if (fos != null) 
	     {
		 fos.close();
	     }
          } 
	  catch (IOException ioe) {
	     System.out.println("Error in closing the Stream");
	  }
       }
   }
}

Output:

File Written Successfully

References:

FileOutputStream – JavaDoc